The present invention is related to heart valve replacement, and more particularly to devices, systems, and methods for transcatheter delivery of collapsible prosthetic heart valves.
Prosthetic heart valves that are collapsible to a relatively small circumferential size may be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility may avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. To place such a valve into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size. For example, a conventional collapsible prosthetic valve is typically collapsed and retained in a collapsed state by a sheath for delivery into the patient, for example, through a femoral artery or through the apex of the heart.
An end of a guide wire may be inserted percutaneously into the artery or the heart of a patient just beyond a desired implant site to establish a guide for an implantable delivery device to follow. The desired implant site is often at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve. Once the delivery apparatus containing the prosthetic valve has reached this site, the valve may be deployed or released from the delivery apparatus and re-expanded to full operating size. For self-expanding valves, the stent automatically begins to expand as the sheath covering the valve is withdrawn.
In certain transapical delivery systems employing self-expanding aortic valves, for example, after the delivery system has been positioned for deployment, the annulus end of the valve may be unsheathed and expanded first, while the aortic end of the valve remains sheathed. Once the annulus end of the valve has expanded, it may be determined that the valve needs to be repositioned in the patient's aortic annulus. To accomplish this, the user (such as a surgeon or an interventional cardiologist) may resheath the annulus end of the valve so that the valve can be repositioned while in a collapsed state. After the valve has been repositioned, the user can again deploy the valve.
Despite the various improvements that have been made to the collapsible prosthetic heart valve delivery process, conventional delivery devices, systems, and methods suffer from some shortcomings. For example, in a conventional delivery device for collapsible prosthetic valves, such as a transapical delivery device 7 shown in FIG. 1, because the aortic valve is not directly aligned with the apex of the heart, it may be difficult to align the longitudinal axis of the distal sheath 8 normally to the geometric center of the native valve annulus 6 (i.e., axial alignment). Without axial alignment, the user will be unable to properly position the prosthetic valve relative to the native annulus 6, such that the valve will not be properly seated in the annulus and therefore will not function properly. Moreover, without axial alignment, the inner wall 3 of the aortic arch 2 may interfere with the advancement of delivery device 7 beyond the native valve annulus 6, and contact between the distal tip 9 of the delivery device and the inner wall of the aortic arch may damage the aorta.
There is therefore a need for further improvements to the devices, systems, and methods for transcatheter delivery of collapsible prosthetic heart valves. Among other advantages, the present invention may address one or more of these needs.